1. Field of Invention
This invention relates to polybenzimidazole polymers. More particularly, the invention relates to the crosslinking of polybenzimidazole polymers.
2. Prior Art
The crosslinking of polybenzimidazole is known in the art. In U.S. Pat. No. 4,020,142, a process for chemically modifying polybenzimidazole membranes to increase the toughness of the membrane is disclosed. Imidazole groups of the polybenzimidazole membrane are crosslinked by the addition of a polybasic acid or an acid chloride. When an acid chloride is utilized, the polybenzimidazole tends to be covalently crosslinked through an amide-type linkage.
In U.S. Pat. No. 4,154,919, another process is disclosed for preparing crosslinked polybenzimidazole. The process involves the reaction of a tetracarboxylic acid dianhydride crosslinking agent with a tetraamine and dicarboxylic anhydride.
Accordingly, it is an object of the present invention to provide a novel process for the crosslinking of polybenzimidazoles.
It is a further object of this invention to prepare crosslinked polybenzimidazoles that will enhance the mechanical properties of polybenzimidazole membranes and other products.
These and other objectives are obtained by preparing the compositions of the present invention.